Perfluoroalkyl phosphite and phosphonate lubricants and lubricant additives



r' 9 2,888,481 Ice Patented May 26. 1 5

PERFLUOROALKYL PHOSPHITE 'PHOSPHO- NATE LUBRICANTS LUBRICANT ADDI- Glenn R. Wilson, Detroit, Mich., assignorto Ford Motor Company, Deni-born, Mich., a corporation of Delaware- I No Drawing. Application February 4, 1957 Serial No. 637,864

1 3 Claims. (Cl. 260-461) This-invention deals with the lubrication art and is particularly concerned with the use of certain perfluoroalkyl phosphorous esters for use as an additive.

It is an object of this invention to provide a lubricant or lubricant additive which exhibits thermal, oxidative, and hydrolytic stability.

With this object in mind, my invention will become apparent upon reading the following specification.

Numerous types of organic materials have been prepared and tested for high temperature applications, each family of compounds has certain advantages and disadvantages. For example dibasic acid esters exhibit excellent lubricity but only fair hydrolytic and thermal stability. The organophosphorus compounds possess good lubricity, fair thermal stability and poor hydrolytic stability. On the other hand, the perfluorocarbons display excellent thermal stability but possess poor lubricity for steel on steel.

I have discovered that a composite structure of certain organophosphorus and perfluorocarbons such as perfluoroalkyl phosphites and perfluoroalkyl phosphonates combine the thermal and hydrolytic stability of the perfluorocarbon with the desirable lubricating properties of the organophosphorus compounds.

As indicated by the phosphite structure I and the phosphonate structure II, each contains tertiary groupings which are generally thought to be prone to hydrolysis. However, the perfluoroalkyl group increases the hydrolytic stability of the compounds by its efiect on the ester linkage Structure I 0 F g i[o c F n (hi-DR R n (n+1) Structure II n=312 R=any alkyl or perfluoroalkyl group containing 1-4 carbon atoms EXAMPLE 1.--PREPARATION OF TRIS(1,1-DI- METHYLHEPTAFLUOROBUTYL) PHOSPHITE This compound was prepared according to the following series of reactions:

(1) 0 omiiocm. 2CH;MgI came 011. ,0M 1 CgHsOMflI (2) C F C(CH OMgI+C I-I OMgI+2H O The 1,l-dimethylheptafluorobutanol in Equation 2 was prepared via the usual Grignard procedure.

The sodium salt of the carbinol, Equation 3, was pre- 2 pared by reacting 120g. of the carbinol with 12.1 g. of metallic sodium sand in 200 ml. of toluene. The solution of the sodium salt wasreacted-with 23.4 g.- of phosphorus trichloride, the sodium. chloride removed from the reaction mixture and the filtrate fractionated at reduced pressure. The tris (1,l-dimethylheptafiuorobutyl) phosphite was isolated as a fraction boiling at 142-9 C.

at 17-18 mm; of mercury.

EXAMPLE Z.,-PREPARATIO N OF BIS(l,1-DI- METHYLH'EPTAFLUOROBUTYL) 1,1 DI- METHYLHEPTAFLUOROBUTYLPHOSPHONATE A mixture of25 g. of tris(1,1-dimethylheptafluorobutyl) phosphite and 10 g. of 1,1-dimethylheptafluorobutyl chloride was refluxed for 4% hours at 150-3 C. and the mixture fractionated. A fraction boiling at 68-77 C./ 5.7-7.5 mm. was obtained. Since the phosphite and phosphonate have identical empirical formulas and both contain P-O-C bonds, their infrared absorption spectra were compared for determining whether or not any conversion of the phosphite to phosphonate had occurred. The infrared spectra, which gave strong evidence for a direct P-C bond absent in the phosphite, indicated conversion of the phosphite to the phosphonate had occurred.

The lubricity of the phosphite prepared according to the procedure described in Example 1 was measured in a precision shell four ball wear tester. The wear-scar diameter was found to be 0.55 mm. at the conclusion of a one hour test at 200 C., 10 kg. load and 1200 r.p.m. This is superior to the wear scar diameter of 0.93 mm. obtained in a test of (2-ethylhexyl) sebacate, a typical lubricant, at 200 C., 10 kg. load and 1200 r.p.m. for one hour.

Tris(1,l-dimethylheptafiuorobutyl) phosphite was also found to be much more thermally stable than its hydrocarbon analog tris(1,1-dimethylbutyl) phosphite, since the latter material decomposed during attempted isolation and purification. A hydrocarbon homolog, tris(tertbutyl) phosphite is known to decompose rapidly at C. while the perfluorophosphite of Example 1 can be heated at C. and C. without apparent decomposition. The hydrolytic stability of the perfiuoro phosphite ester also proved to be greater than its hydrocrabon homologs and analogs. Upon heating a sample of it with water in a selected ampoule at 250 F. for 72 hours the hydrolysis was observed to be only 18% compared with 50% hydrolysis for tris(n-butyl) phosphite. The results of these tests are summarized in Table I.

Table I Max.Stabllity Hydrolysis Compound Temp., 0. at 250 F.

for 72 hours Percent (CIF7C(CH3)20)P 175 18 (CsH7C(CHs):0):P decomposes during preparation. (O5H5C(CH3)20)3P- 80 (C4H:O)sP 50 answer I claim: 1. A composition of matter having the formula:

wherein n is any number from 3-12, and R is an alkyl group having from 1-4 carbon atoms.

2. A composition of matter having the formula:

where n is equal to a number from 3-12 and R is an alkyl group having 1-4 carbon atoms.

3. A lubricant selected from the group consisting of fiuorinated alkyl phosphites and fiuorinated alkyl phosphonates in which the fiuorinated alkyl phosphites correspond to the formula and in which the fiuorinaterl alkyl phosphonates correspond to the formula wherein n is any number from 3-12, and R is an alkyl group having from 1 to 4v carbon atoms,

References Cited in the file of this patent UNITED STATES PATENTS 

3. A LUBRICANT SELCTED FROM THE GROUP CONSISTING OF FLUORINATED ALKYL PHOSPHITES AND FLUORINATED ALKYL PHOSPHONATES IN WHICH THE FLUORINATED ALKYL PHOSPHITES CORRESPOND TO THE FORMULA 